Evaluation of cryogenic shear performance of CFRP laminates

This study seeks to understand the shear performance of CFRP laminates over a wide temperature range including the cryogenic temperatures (lower than -150°C). Experimental evaluations using the v-notched specimens (Iosipescu shear test) to determine the in-plane and out-of-plane (inter-laminar) shear properties (modulus and strength) of CFRP laminates were conducted at three different temperatures (room temperature, -70°C and -160°C). Epoxy-toughened BESFIGHT IM600/#133 CFRP prepreg sheets were used as the material system for experimental investigation. Different correction factors of the v-notched specimens for in-plane and inter-laminar shear modulus determinations at different temperatures were obtained from analytical simulations and they were used to modify the experimental results of shear modulus. It concluded that the cryogenic shear modulus of CFRP laminates for both in-plane and inter-laminar shear becomes about twice of that at room temperature. Failure mechanisms of the in-plane and inter-laminar specimens at different temperatures were also discussed from the experimentally obtained rupture strength. We concluded that the failure strength of inter-laminar specimens becomes higher as the temperature decreases to cryogenic temperatures.